Traditionally, users of Wi-Fi enabled devices have relied on Wi-Fi networks in their home and perhaps their office to gain broadband Internet access. So-called Wi-Fi hotspots in public areas like airports and restaurants have also become quite common. In such networks, an Internet Service Provider (ISP) generally provides a wired Internet connection, and at the point of use a wireless router is set up to provide Wi-Fi access.
In contrast with ISPs, wireless network operators use radio access networks (RANs) to provide access to a core network, with the core network providing connectivity to external packet data networks (e.g., the Internet). However, given the increasing popularity of mobile broadband, wireless network operators are becoming increasingly interested in providing their own Wi-Fi access, through their own distributed wireless access points in a RAN, or through broadband access networks. This could facilitate users relying on a network operator for both their mobile Internet access and also fixed Internet access for generally stationary devices (e.g., home computers, media centers, etc.).
FIG. 1 illustrates a high level example of such an arrangement, in which a wireless terminal 12 is able to access a packet data network 14 (e.g., the Internet) through either a “mobile network” 16 or a “fixed network” 18. The mobile network 16 includes one or more radio base stations, while the fixed network 18 (the so-called “wireline domain”) includes a broadband access network. A Packet Data Network Gateway (PDN-GW) 20 within core network 22 connects the mobile network 16 and fixed network 18 to the packet data network 14. As shown in FIG. 1, wireless terminal 12a is able to transition between the mobile and fixed networks 16, 18. This is sometimes known as “carrier grade Wi-Fi.”
Third Generation Partnership Project (3GPP) mobile networks have a bearer-based mechanism for supporting Quality of Service (QoS) that is defined between a wireless terminal 12 (also known as a user equipment “UE” in some networks) and the PDN-GW 20. A dedicated bearer refers to a tunnel that carries flows sharing the same QoS characteristics. In 3GPP networks, the PDN-GW 20 maintains the downlink bearer mappings, while a UE maintains the uplink bearer mappings. These are used to map the different flows to the appropriate dedicated bearer based on 5 tuples (e.g., source IP address, source port, destination IP address, destination port, and a content identifier). The bearer mappings are created once a dedicated bearer establishment procedure is completed successfully.
As network operators begin to offer both mobile and fixed networks 16, 18, it is desirable to maintain the same QoS over both networks 16, 18. According to current 3GPP procedures, a procedure called “reflective QoS” is used in which downlink QoS is mirrored in the uplink (see, e.g., 3GPP TS 23.139). That is, an n-tuple uplink rule is created by inversing the source and destination addresses (and ports numbers) of the downlink packets and associating with a Differentiated Services Code Point (DSCP) marking contained in the downlink packet, such that the same DSCP marking is used in both the uplink and downlink directions. When an uplink packet is to be sent from a UE to the network over Wi-Fi (e.g., over the fixed network 18), a corresponding uplink n-tuple rule is looked up, and if found, the uplink frame is marked with the appropriate DSCP marking. Reflective QoS ensures that uplink frames are marked in the same way as their corresponding downlink frames.